Various electronic bus systems are known for controlling electrical and electronic components in motor vehicles; hereinafter these will be referred to generally as “bus systems”. In motor vehicle engineering, in particular CAN bus systems (controller area network bus systems) and LIN bus systems (local interconnect network bus systems) are used. CAN bus systems of broad extent are distinguished by a high data throughput rate, but such systems are more expensive that the slower LIN bus systems, due to their relatively high complexity. In particular, CAN bus systems require a two-part data line, whereas LIN bus systems are designed with and function with only a single data line, with savings of substantial line materials. Particularly for this reason, LIN bus systems are used in the motor vehicle industry in a number of systems which are not of safety significance and/or at least for periods of time are assigned a subordinate priority. Examples of such applications which can be controlled with LIN bus systems without problems are: automobile doors, automobile seats, and automobile windows.
In particular, regarding automobile seats, for some time not only have customary electrical seat heating devices been used, but increasingly air conditioning devices have also come to be used. These systems, referred to as “air conditioned seats”, contain not only seat heating means for temperature control, but also a supplemental ventilation system (air supply system) for the seat. The objective of an air conditioned seat is to actively influence the micro-climate at the seat, by cooling and/or ventilation of the contact surface between the occupant of the vehicle and the vehicle seat, in order to increase comfort. Seat air conditioning systems are already known which function via a so-called “master-slave system” and thereby communicate via bus systems. In these systems, the bus master components assume a number of functions, such as e.g. electrical adjustment of the seat position, seat memory management, and/or so-called “seat pneumatics”, and in addition they perform the central control function for the air conditioned seat. Additionally, the master component makes available the corresponding seat heating outputs for connection to additional lines. In a “standard configuration”, the master component assumes the task of decision-making. To the extent that the master component is an “intelligent” unit, it is able to control itself during a control exercise, depending on at least one measured quantity associated with another component (a slave component). The slave components, on the other hand, as a rule, follow control signals from an intelligent component.
Such a system with a LIN control bus is known, e.g. from DE 10 2013 201471 A1. The LIN control bus disclosed there is claimed to have low power consumption and high availability. Further, a so-called “silent” or “still” mode is proposed, which provides a power saving mode for phases in which active control commands are not being exchanged. A transition from this “silent” or “still” mode into an active “monitoring mode” is possible, as soon as it is time for active control of at least one component. However, this arrangement substantially increases the complexity of the bus master, leading to higher costs.
Other seat air conditioning systems are known which are comprised of so-called “seat climate conditioning control units”. These have their own line outputs for vehicle seat heating and ventilation, and they assume a central control function. However, they have the drawback that with vehicle seats which are equipped only with seat heating means, regulation variants arise, e.g. through underequipping or through software conflicts. This leads to increased costs due to the additional development work required, modification of production processes, or logistics problems. Further, with this approach, the available installation space of the climate conditioning unit is not optimally used.